An elastomer composition obtained by blending a butyl-based rubber and Nylon is well known. However, a butyl-based rubber has a low resistance to UV light. If exposed to sunlight, there was a problem of degradation and a significant drop in mechanical properties. As a method for preventing UV degradation, compounding of an amine or phenol-based antioxidizing agent thereto has been the general practice (see PLT 1 below), but these react with the rubber or Nylon and have a detrimental effect on the blend of the rubber and Nylon, and therefore, in the butyl-based rubber/Nylon blends system, there were limits to use and a sufficient effect of prevention of UV degradation could not be obtained. Further, if carbon black is compound into the rubber, it is known in the art that the resistance is given to UV degradation (see PLT 2 below), but in rubber/Nylon blends system, there is the problem that the carbon black in the rubber acts as defects which cause a drop in durability, and therefore, there are limits to the compounding amounts thereof. These also could not give sufficient effects of prevention of UV degradation.